total timing is set at what rpm

Not always and if the motor is on the edge of detonation using the vacuum advance could blow a hole in the piston. Then you really save money on gas cause your motor won't be able to burn anymore of it, ha ha ha.

It comes down to compression ratio, camshaft, gearing-weight of car or truck and the fuel you can buy which is not the same all across the us-canada-any place.

Go for 32 and carefully increase it from there. Better to have not enough timing then too much and blow a piston. Retard timing does cause a motor to run hotter so its best not to unless its pinging.